Figure 1.

Methods. (A, left) All electrodes (e) were lowered into V1 such that they penetrated the cortex perpendicular to its surface. (A, right) Receptive fields (RF) were mapped by moving a bar of light at different orientations across the visual field, as the monkey remained fixated on a spot of light (fix). (B, C) For all trials, an animal fixated a spot for 600 ms (fix) otherwise the trial was aborted and no juice reward was delivered. Two types of trials were used as described in B and C: (B) For visual trials, a visual target (targ) was flashed for 200 ms at the end of the fixation period (fix). The target was set at positive contrast (33%, Michaelson; target luminance = 153 cd/mm²; background luminance = 76.7 cd/mm²) and at 0.25 degrees in size. It was centered in the receptive field of the neurons under study (see panel to the right). Following the termination of the fixation spot and visual target, the monkey was required to depress a lever (lever) with its left hand in order to obtain a juice reward (juice). The monkey was given 800 ms following fixation-spot and target offset to depress the lever. On 50% of trials, control trials during which no visual target was presented were interleaved with the visual trials. For such trials, the monkey was required not to depress the lever in order to obtain a juice reward. For both visual and control trials, the monkey was allowed to generate a saccadic eye movement (sacc) away from the fixation location at the termination of the fixation spot. (C) For stimulation trials, a 100 ms train of electrical stimulation (stim) was delivered to the neurons under study (also see panel to right of B). The stimulation commenced at 200 ms before the end of the fixation period (fix). Following termination of the fixation spot, the monkey was required to depress a lever (lever) with its left hand in order to obtain a juice reward (juice). The monkey was given 800 ms following fixation offset to depress the lever. Depressing the lever indicated that the monkey detected to electrical stimulation. On 50% of trials, control trials during which no stimulation was presented were interleaved with the stimulation trials. For such trials, the monkey was required not to depress the lever in order to obtain a juice reward. For both stimulation and control trials, the monkey was allowed to generate a saccadic eye movement (sacc) away from the fixation location at the termination of the fixation spot.